pgpverify(1)



PGPVERIFY(1)              InterNetNews Documentation              PGPVERIFY(1)

NAME
       pgpverify - Cryptographically verify Usenet control messages

SYNOPSIS
       pgpverify [--findid=string] [--test] < message

DESCRIPTION
       The pgpverify program reads (on standard input) a Usenet control
       message that has been cryptographically signed using the signcontrol
       program (or some other program that produces a compatible format).
       pgpverify then uses a PGP implementation to determine who signed the
       control message.  If the control message has a valid signature,
       pgpverify prints (to stdout) the user ID of the key that signed the
       message.  Otherwise, it exits with a non-zero exit status.

       If pgpverify is installed as part of INN, it uses INN's configuration
       to determine what signature verification program to use, how to log
       errors, what temporary directory to use, and what keyring to use.
       Otherwise, all of those parameters can be set by editing the beginning
       of this script.

       By default, when running as part of INN, pgpverify expects the PGP key
       ring to be found in pathetc/pgp (as either pubring.pgp or pubring.gpg
       depending on whether PGP or GnuPG is used to verify signatures).  If
       that directory doesn't exist, it will fall back on using the default
       key ring, which is in a .pgp or .gnupg subdirectory of the running
       user's home directory.

       INN, when using GnuPG, configures pgpverify to use gpgv, which by
       default expects keys to be in a keyring named trustedkeys.gpg, since it
       doesn't implement trust checking directly.  pgpverify uses that file if
       present but falls back to pubring.gpg if it's not found.  This bypasses
       the trust model for checking keys, but is compatible with the way that
       pgpverify used to behave.  Of course, if a keyring is found in
       pathetc/pgp or configured at the top of the script, that overrides all
       of this behavior.

OPTIONS
       --findid=string
           The --findid flag causes pgpverify to explicitly search for string
           in the output from PGP's analysis of the message.  This option is
           useful when several UIDs are defined on a single PGP key, and the
           caller to pgpverify needs checking whether a given one is defined
           on this key.  In case the signature is valid but does not contain
           string, pgpverify exits with exit status 4.

       --test
           The --test flag causes pgpverify to print out the input that it is
           passing to PGP (which is a reconstructed version of the input that
           supposedly created the control message) as well as the output from
           PGP's analysis of the message.

EXIT STATUS
       pgpverify may exit with the following statuses:

       0   The control message had a good PGP signature.

       1   The control message had no PGP signature.

       2   The control message had an unknown PGP signature.

       3   The control message had a bad PGP signature.

       4   The control message had a good PGP signature but the argument given
           to the --findid flag had non been found in the output from PGP's
           analysis of the message.

       255 A problem occurred not directly related to PGP analysis of
           signature.

ENVIRONMENT
       pgpverify does not modify or otherwise alter the environment before
       invoking the pgp or gpgv program.  It is the responsibility of the
       person who installs pgpverify to ensure that when pgp or gpgv runs, it
       has the ability to locate and read a PGP key file that contains the PGP
       public keys for the appropriate Usenet hierarchy administrators.
       pgpverify can be pointed to an appropriate key ring by editing
       variables at the beginning of this script.

NOTES
       Historically, Usenet news server administrators have configured their
       news servers to automatically honor Usenet control messages based on
       the originator of the control messages and the hierarchies for which
       the control messages applied.  For example, in the past, David Lawrence
       always issued control messages for the "Big 8" hierarchies (comp,
       humanities, misc, news, rec, sci, soc, talk).  Usenet news
       administrators would configure their news server software to
       automatically honor newgroup and rmgroup control messages that
       originated from David Lawrence and applied to any of the Big 8
       hierarchies.

       Unfortunately, Usenet news articles (including control messages) are
       notoriously easy to forge.  Soon, malicious users realized they could
       create or remove (at least temporarily) any Big 8 newsgroup they wanted
       by simply forging an appropriate control message in David Lawrence's
       name.  As Usenet became more widely used, forgeries became more common.

       The pgpverify program was designed to allow Usenet news administrators
       to configure their servers to cryptographically verify control messages
       before automatically acting on them.  Under the pgpverify system, a
       Usenet hierarchy maintainer creates a PGP public/private key pair and
       disseminates the public key.  Whenever the hierarchy maintainer issues
       a control message, he uses the signcontrol program to sign the control
       message with the PGP private key.  Usenet news administrators configure
       their news servers to run the pgpverify program on the appropriate
       control messages, and take action based on the PGP key User ID that
       signed the control message, not the name and address that appear in the
       control message's From: or Sender: headers.

       Thus, appropriate use of the signcontrol and pgpverify programs
       essentially eliminates the possibility of malicious users forging
       Usenet control messages that sites will act upon, as such users would
       have to obtain the PGP private key in order to forge a control message
       that would pass the cryptographic verification step.  If the hierarchy
       administrators properly protect their PGP private keys, the only way a
       malicious user could forge a validly-signed control message would be by
       breaking the public key encryption algorithm, which (at least at this
       time) is believed to be prohibitively difficult for PGP keys of a
       sufficient bit length.

HISTORY
       pgpverify was written by David C Lawrence <tale@isc.org>.  Manual page
       provided by James Ralston.  It is currently maintained by Russ Allbery
       <eagle@eyrie.org>.

COPYRIGHT AND LICENSE
       David Lawrence wrote:  "Our lawyer told me to include the following.
       The upshot of it is that you can use the software for free as much as
       you like."

       Copyright (c) 1996 UUNET Technologies, Inc.  All rights reserved.

       Redistribution and use in source and binary forms, with or without
       modification, are permitted provided that the following conditions are
       met:

       1.  Redistributions of source code must retain the above copyright
           notice, this list of conditions and the following disclaimer.

       2.  Redistributions in binary form must reproduce the above copyright
           notice, this list of conditions and the following disclaimer in the
           documentation and/or other materials provided with the
           distribution.

       3.  All advertising materials mentioning features or use of this
           software must display the following acknowledgement:

             This product includes software developed by UUNET Technologies, Inc.

       4.  The name of UUNET Technologies ("UUNET") may not be used to endorse
           or promote products derived from this software without specific
           prior written permission.

       THIS SOFTWARE IS PROVIDED BY UUNET "AS IS" AND ANY EXPRESS OR IMPLIED
       WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF
       MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
       IN NO EVENT SHALL UUNET BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
       SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
       LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
       DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
       THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
       (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
       OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

SEE ALSO
       gpgv(1), pgp(1).

       <https://ftp.isc.org/pub/pgpcontrol/> is where the most recent versions
       of signcontrol and pgpverify live, along with PGP public keys used for
       hierarchy administration.

INN 2.6.1                         2016-11-06                      PGPVERIFY(1)

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